(1) Field of the Invention
The present invention relates to a hydrogen engine system in which a medium chemically repeating a hydrogen absorption and a hydrogen desorption is mounted.
(2) Description of Related Art
As a conventional system driving an engine by using a hydrogen rich gas generated from a medium chemically repeating a hydrogen absorption and a hydrogen desorption as one of fuels, there is disclosed a hydrogen utilizing internal combustion engine which can supply the medium mentioned above to an engine in addition to the hydrogen rich gas generated from the medium mentioned above, and can independently supply both of them to the engine, for example, as described in patent document 1.
Patent Document 1: JP-A-2005-147124
In an engine system using a hydrogen rich gas generated from a medium chemically repeating a hydrogen absorption and a hydrogen desorption as one of fuels, and driving an engine only by the hydrogen rich gas or by plural kinds of fuels, the engine is driven by storing the hydrogen rich gas generated from the medium in a buffer tank and supplying the hydrogen rich gas stored in the buffer tank to the engine. In order to stably drive the engine, it is preferable to increase a capacity of the buffer tank so as to prevent the hydrogen rich gas from coming short. However, in order to make the engine system compact and light, it is desirable to make the buffer tank compact. In order to make the buffer tank compact, it is important to efficiently generate the hydrogen from the medium as occasion demands. An amount of the hydrogen rich gas generated from the medium is changed in accordance with a medium supplying amount to a catalyst and a temperature of a catalyst material. Since the catalyst temperature is fluctuated in accordance with an operating state of the engine, a reacting amount at a time of generating the hydrogen from the medium, a deterioration state of the catalyst or the like, an amount of the generated hydrogen rich gas is fluctuated in correspondence thereto. In accordance with this, there is generated a state in which a necessary amount of hydrogen rich gas is not generated, and it is hard to execute a linear response to a demanded output of the engine. Accordingly, in order to operate the engine system at a high efficiency, it is necessary to execute a control while taking into consideration the medium supplying amount to the catalyst and the temperature of the catalyst material in correspondence to the operating state of the engine. Further, this problem is similarly generated in the case of using plural kinds of fuels while cutting and separating, it is desirable to select a fuel aspect in correspondence to the demanded output characteristic of the engine or the like, and it is important to efficiently generate the hydrogen rich gas from the medium.
Further, in the case of using the hydrogen rich gas and the medium as the fuel, it is necessary to execute a control while taking into consideration a combustion efficiency and an exhaust performance.
In the system described in the patent document 1, no sufficient study is made about this point.